Stop automatic sleep mode

Hello,

On my iMac (21.5-inch, 2017) with macOS Big Sur version 11.0.1) I installed software "SecuritySpy Version 4.2.12) with which I record surveillance images from cameras. Recently my iMac goes into sleep mode after a few hours and no more images will be recorded How can I adjust my iMac to stay active Or is it the beaking software Thanks.